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Cross-Reactivity Among Cereal Grains
Monday, March 7, 2016
South Exhibit Hall H (Convention Center)
Juliana Guimarães Mendonça, Roberta Almeida Castro, Pablo Torres Cordova, Paula Rezende Meireles, Daniele Danella Figo, Keity Souza Santos, PhD, Jorge Kalil, MD, PhD, Fabio Fernandes Morato Castro, MD PhD, Ariana C. Yang, MD PhD
Rationale: Cross-reactivity among cereal grains is only reported when wheat is involved. We assess three cases of severe anaphylaxis and cross-reactivity to sunflower, oat and rye.

Methods: Patient 1 had colic, vomiting, urticaria and angioedema, 20 minutes after eating 7 grain’s bread with tuna and mayonnaise. Patient 2 presented itching after using moisturizer with oatmeal. Years later, 15 minutes after ingestion of milk, fruits and mixed cereals, he developed urticaria, angioedema, and vomiting. Patient 3, experienced angioedema minutes after oatmeal cookie and in a subsequent exposure, presented rash, angioedema, and dyspnea. Skin prick-to-prick tests were performed with oats, rye, barley, sesame, sunflower seed, soybean, wheat, fruits, tuna and egg. (Except for patient 3 due to atopic dermatitis).  Direct and inhibited Western blots (WB) and Dot Blots were performed with oats, rye and sunflower for the three patients.

Results: SPT: Patient 1 - rye 10x8mm and sunflower 29x15mm. Patient 2 - Oats 8x5mm and sunflower 6x4mm. The WB was positive for three patients for the same cereal that were in SPT (patient 3 positive only for oat). There were several proteins being recognized and pattern of IgE recognition was not the same among different grains tested but inhibition assay showed sunflower was able to inhibit IgE-reactivity to oat and rye.

Conclusions: SPT highlighted the possibility of cross-reactivity between grains, since one tested patient had no clinical history of sunflower hypersensitivity besides positive SPT. Inhibition assay showed sunflower was able to inhibit IgE-reactivity to rye and oat confirming cross-reactivity in two cases.